The slogan of a republic seems inappropriate when looking at the national and international scenario. The Maoists should give up this demand up. Neither India and China are likely to support a call for a republic, nor one for an active monarchy. The ruling Bharatiya Janata Party (BJP) in India supports the Nepali monarchy, but not an active one.
But these national and international trends seem to have given both the right and the left the impression that they use it to push their agenda. The Maoist and pro-palace forces must mend their ways for the sake of the nation and initiate reconciliation. Both the Maoists and palace want a decisive war, which is not good for the country.
It's not feasible to have a constituent assembly immediately, but if the new constitution is endorsed simultaneously by the king and the people then it will not be disadvantageous for Nepal. The way out for the present crisis is to call a round table conference of different political parties and non-political personalities who have a "clean image". An interim government should be formed on the basis of such a conference and that government should negotiate with the Maoists. Any other step is likely to be risky for the king.